Copyright HK Instruments 2021
www.hkinstruments.fi
Installation version 7.0 2021
INSTALLATION
INSTRUCTIONS
HUMIDITY TRANSMITTERS
RHT-MOD Series
• READ THESE INSTRUCTIONS CAREFULLY BEFORE
ATTEMPTING TO INSTALL, OPERATE OR SERVICE THIS
DEVICE.
• Failure to observe safety information and comply with
instructions can result in PERSONAL INJURY, DEATH AND/OR
PROPERTY DAMAGE.
• To avoid electrical shock or damage to equipment, disconnect
power before installing or servicing and use only wiring with
insulation rated for full device operating voltage.
• To avoid potential fire and/or explosion do not use in potentially
flammable or explosive atmospheres.
• Retain these instructions for future reference.
• This product, when installed, will be part of an engineered
system whose specifications and performance characteristics
are not designed or controlled by HK Instruments. Review
applications and national and local codes to assure that the
installation will be functional and safe. Use only experienced and
knowledgeable technicians to install this device.
SPECIFICATIONS
Thank you for choosing an HK Instruments RHT-MOD series rela-
tive humidity transmitter. The RHT-MOD series is intended for use in
commercial environments in HVAC/R applications.
The RHT-MOD measures relative humidity (rH), and temperature (T).
RHT-MOD devices are available with large touchscreen display mak-
ing configuration of the device quick and easy.
RHT-MOD series devices are commonly used to monitor:
• humidity and temperature levels in offices, public spaces, hospitals,
meeting rooms and classrooms
• humidity and temperature in various commercial applications
• humidity and temperature in HVAC/R environment
SPECIFICATIONS
Performance
Measurement ranges:
Temperature: 0...50 °C
Relative humidity: 0–100 %
Accuracy:
Temperature: <0.5 ºC
Relative humidity: ±2...3 % at 0...50 °C and 10–90 % rH
Total error band includes accuracy, hysteresis and
temperature effect over 5...50 °C and 10–90% rH.
Technical Specifications
Media compatibility:
Dry air or non-aggressive gases
Measuring units:
°C and % rH
Measuring element:
Temperature: Integrated
Relative humidity: Thermoset polymer capacitive
sensing element
Environment:
Operating temperature: 0...50 °C
Storage temperature: -20...70 °C
Humidity: 0 to 95 % rH, non condensing
Physical
Dimensions:
Case: 99 x 90 x 32 mm
Weight:
150 g
Mounting:
3 screw holes slotted, 3.8 mm
Materials:
Case: ABS
Protection standard:
IP20
Display
Touchscreen
Size: 77.4 x 52.4 mm
Electrical connections:
Power supply:
5-screw terminal block
(24 V, GND)
0.2–1.5 mm
2
(12–24 AWG)
Relay out:
3-screw terminal block
(NC, COM, NO)
0.2–1.5 mm
2
(12–24 AWG)
Electrical
Input: 24 VAC or VDC, ±10 %
Current consumption: max 90 mA (at 24 V) +
10 mA for each voltage output or 20 mA for
each current output
Relay out:
SPDT Relay, 250 VAC / 30 VDC / 6 A
Adjustable switching point and hysteresis
One analog output for selected media:
0/2*–10 VDC, Load R minimum 1 kΩ
*(2–10 VDC display models only)
or
4–20 mA, maximum load 500 Ω
Communication
Protocol: MODBUS over Serial Line
Transmission Mode: RTU
Interface: RS485
Byte format (11 bits) in RTU mode:
Coding System: 8-bit binary
Bits per Byte:
1 start bit
8 data bits, least significant bit sent
first
1 bit for parity
1 stop bit
Baud rate: selectable in configuration
Modbus address: 1−247 addresses selectable in
configuration menu
Conformance
Meets requirements for CE marking:
EMC Directive 2014/30/EU
RoHS Directive 2002/95/EC
LVD Directive 2014/35/EU
WEEE Directive 2012/19/EU
INTRODUCTION
WARNING
APPLICATIONS
COMPANY WITH
MANAGEMENT SYSTEM
CERTIFIED BY DNV GL
= ISO 9001 = ISO 14001 =
RoHS 2
2011/65/EU